The Daleks manage to construct their own time machine and begin pursuing
the TARDIS across time and space with the singular intent of capturing and
killing the Doctor, Ian, Barbara and Vicki. The chase brings the time
travellers to a dying desert planet, the Empire State Building, the
Mary Celeste, a haunted house, and finally Mechanus, a planet
dominated by robotic Mechonoids from which they may never escape.

Production

Fresh from completing The Dalek Invasion Of
Earth earlier in 1964, Terry Nation was hastily commissioned to
write another Doctor Who story on October 6th by new story editor
Dennis Spooner. This serial, intended to wrap up the second production
block, was originally planned to be six episodes long. After the decision
was made to reedit the third and fourth installments of Planet Of Giants into one single twenty-five
minute episode, thought was briefly given to extending Nation's storyline
to seven parts as compensation, though this was never pursued.

By mid-December, however, Nation's idea was abandoned, and on December
16th he was commissioned to write a new six-episode serial in its place.
Accorded the functional title of “Daleks III”, this adventure
would feature a third encounter between the Doctor and the
increasingly-popular Daleks. Early in 1965, a further nine episodes were
allocated to Doctor Who's second production block. One of the
constituent stories would be retained as part of Season Two (with the
remaining episodes held over to lead off the third season), and so this
meant that Nation's adventure would no longer be the season finale.

The Chase would introduce a
major new monster: the Mechonoids

As with the Zarbi in Bill Strutton's The Web
Planet, which was in production while Nation was drafting his
scripts for Serial R -- now called “The Pursuers” -- the Dalek
sequel would feature the introduction of a major new monster. These were
the Mechons, whose name was eventually changed to “Mechonoids”
(although this would be misspelt “Mechanoid” in the closing
credits, and on subsequent merchandise); their planet was first
“Mechon” and then “Mechanus”.

The denizens of Aridius (originally “Aridus”) were envisaged as
ugly, hunchbacked creatures. Nation's drafts originally introduced the
Fungoids on Aridius, as opposed to confining them solely to the Mechanus
sequences. The Doctor's explanation of the haunted house existing in a
realm of human thought was in fact Nation's initial concept for the
segment, which producer Verity Lambert felt was straying too far from the
conventional Doctor Who approach; Baron Frankenstein was at one
point included in these scenes, while the Grey Lady was a late addition.
Nation discarded several further ideas for the serial, including sequences
set in ancient Egypt (where the first of the Great Pyramids would be
erected over the remnants of a destroyed Dalek), the planet Stygian whose
inhabitants were invisible, and the mist-shrouded world of Vapuron. These
ideas would subsequently be recycled in The Daleks'
Master Plan.

Another amendment made to the story -- which once again became generically
referred to as “Dalek Three” -- was the introduction by
Spooner of the Time-Space Visualiser (given to the Doctor at the end of
the previous story, The Space Museum),
replacing the “Time Curve Visi-Scope”, which Nation had
conceived as an invention of the Doctor's. The Visi-Scope/Visualiser scene
originally depicted the time travellers watching a speech by Winston
Churchill instead of a performance by the Beatles. At one point, Anne
Hathaway appeared in the Shakespeare scene.

During the early months of 1965, both William Russell and Jacqueline Hill
were contemplating leaving Doctor Who upon the expiry of their
contracts with the Dalek story. Nation was therefore asked to include a
new character in his scripts to replace Ian in the regular cast; this was
an astronaut named Roger Bruck. Due to the uncertainty surrounding the
lead cast, Nation elected not to write the final scenes of the serial,
which had acquired its final title of The Chase, instead leaving it
to Spooner to determine the fates of Ian, Barbara and Roger. Around early
May, by which time it was known that both Russell and Hill would indeed be
leaving Doctor Who, the new companion became known as Michael
Taylor.

The new companion was an astronaut named Roger Bruck, who
then became known as Michael Taylor

Richard Martin, who had been involved with both previous Dalek stories,
returned to direct The Chase, having recently completed The Web Planet; Christopher Barry had earlier
been considered for the post. Martin was reunited with Ray Cusick, the
designer who had created the Daleks' visual appearance for their debut
story. Cusick was unhappy with the modifications made by Spencer Chapman
on The Dalek Invasion Of Earth, such as a
rear-mounted radio dish and larger fenders, and had these removed. Unlike
that serial, no new Daleks had to be constructed for The Chase,
although two casings from the Aaru film Dr Who And The Daleks were
refurbished and used in the background of some scenes.

Production began with a day's location filming on April 9th at Camber
Sands in East Sussex, which doubled as the surface of Aridius. Action then
moved to the Ealing Television Film Studios, where filming took place from
the 12th to the 15th. This involved the historical “footage”
which would appear on the Visualiser, the Mary Celeste scenes, and
the battle between the Daleks and the Mechonoids.

The original idea for the Beatles segment was to depict the band
performing at a fiftieth-anniversary concert, with the Fab Four dressed up
as old men. It appears that the musicians themselves were interested in
the proposition, but it was vetoed by their manager, Brian Epstein.
Subsequently, it was thought that an appearance by the Beatles on Top
Of The Pops might be used instead, but no footage was available as
most editions of the programme were destroyed after broadcast. A November
1964 recording of I Feel Fine was then considered. In the event,
however, footage of the band performing Ticket To Ride at Riverside
Studios on April 10th was made available to Martin's team.

The Executioners was recorded on April 30th; as usual, all six
installments of The Chase were taped on Fridays. This evening saw
Doctor Who return to its regular studio home of Riverside 1 after a
brief relocation to Television Centre for The Space
Museum. On May 6th, director Douglas Camfield (who had recently
handled The Crusade) and a stills photographer
accompanied William Russell and Jacqueline Hill on an excursion to several
London landmarks. Images taken at this time would later be inserted into
the final episode of The Chase. On May 10th, Camfield also
supervised the filming of the London bus segment at Ealing while working
on his own assignment, The Time Meddler.

After playing Morton Dill in episode three, Peter Purves
was recommended to Verity Lambert for the part of the new companion

Part three, Flight Through Eternity, was recorded on May 14th. Cast
as obnoxious tourist Morton Dill in this episode was Peter Purves, whom
Martin had passed over for a role as a Menoptra in The Web Planet. Purves had abandoned teaching for
acting, gaining some experience in repertory theatre before being cast in
a handful of television programmes, including episodes of Z Cars,
Armchair Theatre and Court Martial (the latter two under the
direction of Hill's husband, Alvin Rakoff). Purves proved popular with
several members of the Doctor Who team, and he was recommended to
Lambert for the part of the new companion, Michael. Lambert and Spooner
concurred, and offered Purves the role upon the completion of Flight
Through Eternity. Purves spent the next week working with Spooner to
better define the character; around this time, his name was changed to
Steven.

On May 21st, Purves was formally contracted to play the new
companion through the first story of the next recording block. Also on
that day, Maureen O'Brien received a contract extension covering the same
period, while on the 24th, William Hartnell was retained through Serial Y,
midway through Season Three.

In episodes four and five, Edmund Warwick joined the cast to play the
Doctor's robotic doppelganger in scenes involving both the real and
artificial Doctors. According to Warwick, this part was written especially
for him, as a thank-you for his emergency replacement of Hartnell when the
latter was injured while rehearsing an episode of The
Dalek Invasion Of Earth. The decision was made to confine
Warwick's appearances to long shots, and to dub over Hartnell's voice for
all the robot's lines. Unfortunately, one piece of dialogue was not
replaced, and was transmitted in Warwick's own voice. Unusually, recording
on the fifth episode, The Death Of Doctor Who, began in the
afternoon rather than the evening. This was arranged to capture the
sequence of the Doctor fighting with the robot, which would
be physically taxing for Hartnell to perform.

The Planet Of Decision, recorded on June 4th, saw the return of
Purves, now playing Steven Taylor. Unfortunately, the Mechonoids proved
less than successful as monsters, their unwieldy bulk making them very
difficult to use effectively. As a result, they would join the Zarbi of
The Web Planet in the ranks of monsters which
would endure primarily in Doctor Who spinoffs, such as the TV
Century 21 Dalek comic strip, rather than the programme itself.

June 4th was the final day on Doctor
Who for both William Russell and Jacqueline Hill

Due to the need for Spooner to write the next serial in production, The Time Meddler, this was the final story on
which he was credited as story editor. In principle, Spooner handed over
the job to Donald Tosh at this stage; Tosh had been trailing him
throughout the production of The Chase. However, Spooner would
continue to do some uncredited story editing for several more weeks.
Spooner moved over to join Nation as writer and assistant editor on
The Baron. In addition to writing further episodes of Doctor
Who, Spooner provided scripts for a variety of series, including
Doomwatch, UFO, and The New Avengers. He was a script
editor on Bergerac, and helped create programmes such as Randall
And Hopkirk (Deceased). Spooner died of a heart attack on September
20th, 1986.

This was also the final day on Doctor Who for both Russell and
Hill. Hartnell was particularly upset about their departure, which left
him as the lone original regular remaining on the show. Ironically,
Russell and Hill would immediately find themselves reteamed in a stage
version of Separate Tables.

William Russell would subsequently concentrate on the theatre, although he
continued to make a variety of appearances both on television and film,
sometimes under his real name of Russell Enoch. These would include a
regular role on the long-running soap opera Coronation Street, an
episode of The Black Adder, and a cameo as a Kryptonian Elder in
the 1978 feature film Superman. In 1999, Russell appeared on the
BBC Video release of Doctor Who: The Crusade And The Space Museum,
to record links for the missing episodes of The
Crusade in character as Ian Chesterton. Russell also recorded
narration for several BBC Radio Collection Doctor Who releases, and
appeared twice in audio plays for Big Finish Productions, first as Lord
Darzil Carlisle opposite Peter Davison's Fifth Doctor in The
Game (2004), and latterly as Ian Chesterton in 2009's The Transit
Of Venus.

Shortly after leaving Doctor Who, Hill retired from acting to raise
a family, but returned to television in 1979. She appeared in programmes
such as Romeo And Juliet and Tales Of The Unexpected, as
well as accepting the role of Lexa in the 1980 Doctor Who story
Meglos. Jacqueline Hill died of cancer on
February 18th, 1993.